Advertise virtually anything here, with CPM banner ads, CPM email ads and CPC contextual links. You can target relevant areas of the site and show ads based on geographical location of the user if you wish.

Yes, sometimes they refund clicks to the advertiser.
For example: When some dude starts clicking several links with a bot, they *might* refund the clicks.
If they do, they also substract it from your clicks ... I believe you should see this in the performance reports though

It is the home page only that shows this problem, your earning will not be affected .
This is Google team reply :
Hi,

Thanks for your patience. I've verified that the issue affecting your account affects only the displaying of your earnings, so your earnings will be paid as usual after you have crossed your payments threshold. In the meantime, you can view an estimate of your monthly earnings by visiting your reports page.

Our engineers are working as quickly as they can to investigate this issue and hope to have a fix soon. Thanks for your patience in the meantime!